Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the default request shape, that results are the source card records with page counts, and that filter slugs must be validated through the companion tool. It does not discuss pagination limits or how invalid filter values are handled.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with purpose and ending with the discovery pointer and default. No filler, and the long first sentence is dense with substance rather than padding.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 35 optional parameters, an output schema, and read-only annotations, the description covers purpose, defaults, and how to obtain valid filter values, which is the essential context. Gaps are minor: no guidance on pagination interaction between page and pageSize, and no note that many filter parameters are upstream-native and may be silently ignored.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3; the description earns a bump by framing all 35 parameters as the card gallery's native controls and by stating the default request (all-class Standard set), which the schema does not say. However, the schema already repeats the 'discover values with hearthstone_filters' pointer on most parameters, so the description's marginal semantic value is modest. Note the naming mismatch: the description points to hearthstone_card_filters while the schema says hearthstone_filters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource — 'List one page of public Hearthstone cards' — and enumerates the filter families (sets, classes, Battlegrounds, Mercenaries, card backs, text search, sorting), so the agent knows exactly what this tool returns. It never explicitly distinguishes itself from the singular sibling hearthstone_card, so the plural-listing boundary is only implied by 'one page'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear operational context: discover valid filter values and sort slugs with hearthstone_card_filters, and it notes the default request is the all-class Standard set, which tells the agent what happens with no arguments. It stops short of stating when NOT to use this tool (e.g. fetching a single card by id), leaving that routing to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.